In presses die tools and moulds need to be moved in and out of a press table on a regular basis. U.S. Pat. No. 4,691,554 describes a die transfer system which is based on vertically movable rails provided with rollers. Each movable rail is provided in an inverted T-slot and comprises an air bag which can be inflated in order to elevate the rollers vertically to a position above the upper surface of the table. Thus it is possible to grip the die tool or mould and, with the application of a force, roll it out of the press, or vice versa. A problem with the die transfer system of U.S. Pat. No. 4,691,554 is, however, that manual force or a special gripping device is required to move the die.
A known solution to this problem is to provide, in each of the inverted T-slots of a table, a bar which slides on a strip of metal provided on top of an air bag located at the bottom of the inverted T-slot. The bar is, at one end, connected to a hydraulic cylinder adapted to force the bar in a horizontal direction. In order to move a die tool from the table the air bag is first inflated. When inflated the air bag lifts the strip, and thus the bar, vertically upwards to lift the die tool or mould a short distance from the surface of the table. The hydraulic cylinder then acts on the end of the bar to drag the bar, and the mould or die tool resting thereon, horizontally out of the press, the bar sliding on the strip.
A problem with this bar solution is, however, that it takes up considerable space in the area of the press and increases the demand for floor area required for each press.